Wear resistant, textured resinous compositions

ABSTRACT

Wear resistant resinous compositions having textured or embossed surfaces resulting from the process which comprises selectively contacting a resinous polymer containing a blowing agent dispersed therein with an inhibitor for said agent, applying thereto a self-supporting layer of a translucent, decorative, resinous wear layer, and, thereafter heating the resulting assembly so as to effect the decomposition of the blowing agent and the resultant expansion on the surface of the resinous composition as well as to fuse the wear layer which has conformed to the surface embossings.

United States Patent Shortway et al. v

[54] WEAR RESISTANT, TEXTURED RESINOUS COMPOSITIONS [72] Inventors:Harry A. Shortway, Glen Rock; Alan A.

Graham, Mercerville; Robert D. Mansolillo, Bloomfield, all of N.J.;Joseph F. Dobry, Langhorne Manor, Pa.

[73] Assignee: Congoleum Industries, Inc., Kearney, NJ.

[22] Filed: Mar. 14, 1969 [21] Appl, No.: 807,269

[52] U.S. Cl ..l56/79, 264/48, 264/54, 156/277 [51] Int. Cl ..B32b 5/18[58] Field of Search ..l56/54, 78, 79, 277; 264/48 [56] References CitedUNITED STATES PATENTS 3,293,094 l2/l966 Nairn et al. ..l56/79TRANSLUCENT WEAR LAYER 1451 May 2, 1972 3,365,353 1/1968 Witman ..156/79x 3,373,072 3/1968 101168.... ....156/79 x 3,458,337 7/1969 Rugg 156/79x Primary ExaminerBenjamin R. Padgett Assistant Examiner-S. R. HellmanAttorney-Richard T, Laughlin [5 7] ABSTRACT 20 Claims, 2 Drawing FiguresDECORATIVE CHIPS CELLULAR STRUCTURE BACKING INHIBITED SUBSTANTIALLY NON-CELLULAR STRUCTURE PATENTEU MAY 2 I RESINOUS L aLowINs AGENT COMPOSITIONM' SHEET FORMING INK CONTAlNlNG INHIBITOR APPLYIPREFORMED wEAR LAYERHEATING To EAcT BLOWING AGENT AND INHIBITOR HEATING To DECOMPOSE BLOWINGAGENT AND FUSE REsINous LAYERs PRODUCT HG I TRAAYSLUCEBIQT WE LAYEoEcoRATIvE CHIPS CELLULAR sTRucTuRE I INVENTORS EA: 3." gm ROBERT D.MANSOLILLO r BY JOSEPH F. DOBRY BACKING INHIBITED SUBSTANTIAL NON-CELLULAR STRUCTURE ATTORNEY WEAR RESISTANT, TEXTURED RESINOUSCOMPOSITIONS BACKGROUND OF THE INVENTION Sheets of resinous compositionhave found widespread use as decorative and wear-resistant coverings fora wide range of products. Such sheets, for example, are used extensivelyas wall, floor and table coverings, book covers, decorative containers,as fabrics for use as upholstery, clothing and automobile interiors, andthe like. In many instances, the resinous composition sheets are appliedor formed on backings such as woven fabrics, paper, felt, metal, wood,glass, and the like. These backing materials have many purposes, themost common being added strength and serviceability. It is commonpractice to emboss the surface of such sheets to give added decorativeappeal and, in many instances, further utility. Typical of the types ofembossings are those which simulate leather or textured cloth, such aslinen. In some instances, the embossed areas are filled in withpigmented ink by techniques known as spanishing or valley printing."

The introduction of cellular resinous compositions has led to theirincorporation in products such as recited above, either alone, or incombination with non-cellular resinous composition surface wear layersand/or backing webs. The cellular foam sheet gives the product variousdesirable properties, depending on the type of cellular foam, such ashigh resiliency and good feel or hand.

Embossing of resinous composition sheets is conventionally accomplishedwith an embossing roll or plate which has been engraved or otherwisetreated to create the design desired in raised relief on its surface.The sheet and/or embossing surface is heated and the design pressed intothe heat-softened sheet.

Various methods have been suggested for producing cellular foam productshaving a textured or embossed surface without utilizing embossing rolls.Embossing rolls are expensive to produce and when combined with a valleyprinting operation are difficult to control. In some instances, it isdesired to print a design and thenemboss in register with the design.Such an operation requires very complex equipment. Additionally,embossing of curved or irregular surfaces is very difficult.

One method which eliminates embossing rolls is disclosed in U.S. Pat.No. 2,961,332 which issued to R. Frank Nairn on Nov. 22, 1960. Inaccordance with this patent, a layer of foamable resinous composition isformed on a base by printing a number of different resinous compositionseach containing its own amount or type of blowing agent. The layer isthen heated to decompose the blowing agent and fuse the composition. Theproduct has an irregular or textured surface conforming to the amount ortype of blowing agent in the various printed compositions. Anothermethod is disclosed in U.S. Pat. No. 2,964,799 which issued to P. E.Roggi et al., on Dec. 20, 1960. According to this patent, a foamableresinous composition is formed into a self-supporting sheet of fusedcomposition. Heat is then applied to the foamable composition sheet atvarious points to cause the blowing agent at those points to decomposeand form a cellular structure. The raised areas in the finished sheetcorrespond to the points of heat application. U.S. Pat. No. 2,825,282which issued to J.B. Gergen et al., on Mar. 4, 1958, discloses a relatedmethod for producing a letterpress makeready. In accordance with thislatter patent, a foamable composition is formed into a sheet and thenprinted with inks containing radiant energy-absorbing pigments. Onexposure of the sheet to radiant energy, the blowing agent in contactwith the pigments receives more intense heat and, therefore, willdecompose and form cellular foam without affecting the unprintedportions of the sheet. As is apparent, the heating must be very rapidand carefully controlled.

An embossing technique which has become known as chemical embossing hasproven to be a vast improvement over the procedures of the prior art isdisclosed in U.S. Pat. Nos.

3,293,094 and 3,093,108, which issued to R. Frank Nairn et a] on Dec.20, 1966. In this procedure, the decomposition temperature of a chemicalblowing agent dispersed in a resinous polymer composition is controlledby applying an inhibitor to the surface of the composition. Thesubsequent application of heat selectively decomposes the blowing agent,thereby resulting in the formation of either depressed or raised areasin the final product at the points of inhibitor application.

In many instances, the embossed products have been coated with atransparent protective layer which serves to provide wear resistance,resistance to attack by household chemicals, resiliency and stainresistance, etc. Although most prior art wear layers have performedsatisfactorily, certain disadvantages have been inherent in their usewhen their thickness has exceeded about 0.014 inch. Thus, the fluidityof typical wear layer compositions of such thickness, at processingtemperatures, has caused the wear layer composition to flow into andpartially fill the depressed areas developed in the chemically embossedproducts. As a result, substantial reduction in the fluidity and depthof embossing has occurred. Although it would be expected that calenderedwear layers containing fillers which can be laminated to the foamablegel would overcome this problem, such calendered sheets exhibitexcessive resistance or spine and therefore, are unable to readilyconform to the embossings and in many instances bridge the depressed(embossed) areas. In order to compensate for this excessive resistance,lower gauge wear layers have necessarily been utilized, thus severelyrestricting the applicability of the final product in areas of heavy usewhere stronger, more resistant wear layers are required.

Higher plasticizer concentrationswhich seek to improve the flexibilityand fluidity of such wear layers have adversely effected the hand orfeel of the final product as well as thestain resistance of the wearlayer. In addition, most of the plastisol compositions which have beenutilized as wear layers have been transparent. The transparency enablesthe printed design below the surface of the wear layer to be observedand thus compensates for the reduced definition of the embossed areas.However, by magnifying the printed appearance,'the transparent areasminimize the continuous, natural geometric appearance which is desiredin the final product. I

SUMMARY OF THE INVENTION The primary object of this invention is toprovide an embossed surface covering of novel constructionJAnotherobject is to provide a wear layer for such a covering which providesexcellent performance and decorative characteristics while substantiallyovercoming the disadvantages present in the prior art wear layercompositions. A further object is to maintain, in these novel products,the advantages which are derived from chemical embossing techniques.Various other objects, and advantages of this invention will be apparentfrom the following detailed description thereof.

It has now beendiscovered that it is possible to produce superiorresinous cellular foam products having embossed surfaces by contactingthe surface of a resinous polymer containing a heat decomposable blowingagent dispersed therein with an inhibitor for said blowing agent,applying thereto a coating of a translucent, decorative, resinous wearlayer, at least about 0.014 inch in thickness, as hereinafter described,and thereafter applying heat to the assembly in order to effect thedecomposition of the blowing agent and the resultant expansion on thesurface of the resinous composition as well as to fuse the protectivewear layer.

It is to be noted that the resulting products combine the advantagestypically derived from a chemical embossing technique with the uniqueperformance characteristics exhibited by the specified wear layercompositions. Thus, this discovery makes possible the production of aproduct having embossed surfaces which can be in complete register witha printed design. Additionally, the discovery makes possible theutilization of any type of printing apparatus as an embosser,

thereby eliminating the need for expensive embossing rolls and relatedequipment. Further, it allows the embossing of a surface withoutexerting pressure on the surface and without regard to the shape orcontour of the surface.

The unique wear layers which are applied to these products exhibitsuperior wear resistance, resistance to attack by household chemicals,resiliency and stain resistance. Of great importance, these wear layersare sufficiently fluid at the temperatures utilized to decompose theblowing system so as to enable them to readily flow and conform to theembossings which subsequently develop. As a result, such wear layers arecapable of being applied in heavier thicknessesthan conventionalplastisol wear layers, thereby providing additional protection in heavyduty application areas. They provide increased definition of theembossed regions when compared with conventional products at comparablewear layer thicknesses. They exhibit better hand and improved stain resistance as a result of the low plasticizer concentrations which may beutilized in their formulation. The translucency of these wear layersenables them to mask the printed look of the embossed product whilestill exhibiting the desired textured appearance. Furthermore, thesewear layers may exhibit a large variety of decorative effects.

The number of products which can be produced by the process of thisinvention is unlimited. These products can be used in floor, wall, tableand countertop coverings, and the like and, in fact, wherever resinousplastic sheets or compositions exhibiting surface wear resistance arerequired. Many additional applications of this invention will occur tothose skilled in the art.

Our invention will be better understood from the following detaileddescription thereof together with the accompanying self-explanatorydrawings in which:

FIG. 1 is a flow diagram of atypical embodiment of the process of thisinvention, and

FIG. 2 is an enlarged cross-sectional view of the final embossedproduct.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The backing web utilized willdepend in large measure on the product to be produced. If the backingweb, is to remain as part of the finished product, then it can beformedof a resinous composition, felted sheet, woven or knitted fabricor the like. Any of the thermoplastic or elastomeric resinouscompositions which can be formed into a sheet can be used to formbacking sheets for use in the invention. Typical of the resins'which canbe'compounded with plasticizers and fillers and sheeted to form a sheetare such resins as butadienestyrene copolymers, polymerized chloroprene,polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetatecopolymers and the like. In some cases, scrap and degraded resinouscompositions can be salvaged by forming them into sheets which can beused as backing sheets in producing products in accordance with theinvention.

As indicated, suitable backing sheets also include woven fabrics formedof such fibers as cotton, wool, asbestos and various synthetic fibers.Where loosely woven fabrics such as burlap are used, the fabric can besized to prevent passage of the coating composition through the openingsbetween the fibers by utilizing the conventional sizing composition usedin the textile industry or a very viscous application of the coatingcomposition which is to be applied. The coating can be dried or hardenedquickly before it passes through the fabric.

It is sometimes desirable and particularly when thebase is a felt sheetto apply a size coat prior to the application of the first coating. Thesize coat serves as a barrier coat to prevent migration of the feltimpregnant into the coat. In addition, the size coat serves to providegood adhesion between the base sheet and the first coat. The size coatis preferably applied as an aqueous emulsion of a suitable resinalthough it can be applied as a plastisol or the like. Acrylic resinsand vinyl chloride polymers have been found particularly useful for thispurpose.

If the backing is to be removed from the final product, it is preferablya release paper. Such a paper conventionally has a coating on itssurface to allow the plastic sheet to be easily stripped from'the paper.Typical coatings used are clays, silicone compositions, polyvinylalcohol, and similar special compositions well-known in mean.

In accordance with the invention, a foamable resinous polymercomposition is applied to the base. The resinous binder is preferablyone that is coalesced or fused into a continuous film by the applicationof heat since this allows gelling of the composition to produce a goodprinting surface. In this specification and claims, the term fused" isintended to mean that statewhich is achieved in a resinous compositionduring the transition froma random dispersion or suspension of discreteresin particles in plasticizer to one of a homogenous consistency anduniform viscosity and rheological characteristics.

The foamable composition is also preferably a dispersion of resin ,in aliquid medium. The dispersion medium can be water in the case of 'anaqueous latex, organic solvent as an organosol or plasticizer as aplastisol. Best results have been obtained with a dispersion of resinvin a plasticizer which is conventionally termed a plastisol. A plastisolhas appreciable fluidity at normal room temperature, but is converted byheat into a fused, flexible, tough thermoplastic mass. Plastisols arepreferred since it is unnecessary to remove large volumes of carrier asis necessary with a latex or organosol. The composition can also be amixture of dry blend and blowing agent. The dry blend is resin particleshaving plasticizer absorbed on their surface. The dry blend with theaddition of stabilizer, pigments and .the like can be mixed with theblowing agent and distributed on a base in a smooth layer. The layer isthen heated to either form a porous sheet or to fuse partially orcompletely the composition into a solid sheet. The inhibitor can then beapplied to the sheet thus formed in any suitable manner. With the poroussheet modification, the penetration of the inhibitor is simplifiedbecause of the porous nature of the sheet. Such sheets are normallythereafter heated and subjected to a pressing operation to densify thesheet.

. The preferred and most widely used resin for surface coverings arepolymers of vinyl chloride. The vinyl chloride polymers can either besimple, unmixed homopolymers of vinyl chloride or copolymers,terpolymers or the like thereof in which. the essential polymericstructure of polyvinyl chloride is interspersed at intervals with theresidues of other ethylenically unsaturated compounds polymerizedtherewith. The essential properties of the polymeric structure ofpolyvinyl chloride will be retained if not more than about 40 percent ofthe extraneous comonomer is copolymerized therein. Suitable extraneouscomonomers include, for instance, vinyl bromide, vinyl fluoride, vinylesters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate, otherfatty acid vinyl esters, vinyl alkyl sulfonates, and the like; vinylethers such as vinyl ethyl ether, vinyl isopropyl ether, vinylchloroethyl ether and the like; cyclic unsaturated compounds such asstyrene, the monoand polychlorostyrenes, coumarone, indene, vinylnaphthalenes, vinyl pyridines, vinyl pyrrole and the like; acrylic acidand its derivatives such as ethyl acrylate, methyl methacrylate, ethylmethacrylate, ethyl chloroacrylate, acrylonitrile, methacrylonitrile,diethyl maleate, diethyl fumarate and the like; vinylidene compoundssuch as vinylidene chloride, vinylidene bromide, vinylidenefluorochloride and the like; unsaturated hydrocarbons such as ethylene,propylene, isobuteneand the like; allyl compounds such as allyl acetate,allyl chloride, allyl ethyl ether and the like; and conjugated andcross-conjugated ethylenically unsaturated compounds such as butadiene,isoprene, chloroprene, 2,3- dimethylbutadiene-1,3-piperylene, divinylketone and the like. Although such vinyl chloride resins are preferred,as is apparent, the compositions can be formed from any resin which canbe foamed with a blowing agent and the invention is not intended to belimited to any particular resin or group since many other types andgroups of resins will occur to those skilled in the art and theparticular resin selected does not form part of the invention. Otherresins which can be mentioned, however, are polyethylene; polypropylene;methacrylates; synthetic rubber, such as neoprene, silicone, SBR andnitrile; polyurethanes; polyamides; polystyrene; phenolics,urea-formaldehydes; cellulose esters; epoxies and silicones.

Resins adaptable for use in formulating vinyl plastisols are commonlyreferred to as dispersion grade resins. Such resins are available havingparticle sizes of from about 0.02 to about 2 microns in contrast tocalendar grade vinyl resins which are available in particle sizesranging up to 200 microns. Dispersion grade resins are usually of highermolecular weight than calendar grade resins and have particle surfacesof a hard, horny nature. Polymers of vinyl chloride having specificviscosities above about 0.25 and preferably between 0.30 and 0.70 asmeasured in a solution of 0.4 gram of resin in 100 milliliters ofnitrobenzene at 30 C. are particularly effective. (ASTM Dl243-60.)Specific viscosity is a comparison of the blow time for a control ofpure nitrobenzene solvent as compared to the solution of nitrobenzeneand resin. The specific viscosity is determined as the sample flow timedivided by the control flow time, minus 1. The specific viscosity is aneffective measure of relative molecular weight of the polymer, thehigher the specific viscosity the higher being the molecular weight.

In the formulation of plastisol compositions for use in the invention,the fine particle size resin is uniformly dispersed in a mass of fluidplasticizer. The fluidity of plastisols is influenced in part by theparticular resin and plasticizers selected, but is also a function ofthe ratio of plasticizer to resin. Plastisols become less fluid as theratio of plasticizer to resin is reduced. Coating compositions for usein the invention preferably contain from about 20 to about 150 partsplasticizer per 100 parts resin with a range of about 50 to about 80parts plasticizer per 100 parts resin being particularly effective. Theviscosity of plastisol compositions can also be reduced by addition ofsmall amounts of a volatile diluent not exceeding about parts per 100parts resin; it being required that the diluent have no solvating effecton the resin. Useful diluents include benzene, toluene, methyl ethylketone, petroleum solvents such as V.M. and P. naphtha (boiling range ofl90-275 F.) and the like.

Organosols for use in the invention preferably contain about to about 55parts of plasticizer per 100 parts of resin with about 30 to 40 parts ofplasticizer per 100 parts of resin being particularly preferred, whereasplastisols usually contain about 45 to about 150 parts of plasticizerper 100 parts of resin. The amount of solvent utilized depends in largemeasure on the coating viscosity best suited for the coating apparatusutilized.

The selection of the plasticizer is important in determining thestrength and flexibility of the coating and also in influencing theviscosity and viscosity stability of the composition and the foamingcharacteristics of the foamable composition. Esters of straight andbranched chain alcohols with aliphatic acids impart low viscosity andgood viscosity stability. Typical plasticizers of this type includedibutyl sebacate, dioctyl sebacate, dioctyl adipate, didecyl adipate,dioctyl azelate, triethylene glycol di (2-ethylhexanoate), diethyleneglycol diperlargonate, triethylene glycol dicaprylate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, and the like. Plasticizers of thearomatic type, such as esters of aliphatic alcohols and aromatic acidsor aromatic alcohols and aliphatic acids or aromatic alcohols andaromatic acids are desirable in that they impart good'foamingcharacteristics to a plastisol, although the use of highly aromaticplasticizers is limited by their tendency to yield plastisols of highviscosity. Typical plasticizers of this type include dibutyl phthalate,dicapryl phthalate, dioctyl phthalate, dibutoxy ethyl phthalate,dipropylene glycol dibenzoate, butyl benzyl sebacate, butyl benzylphthalate, dibenzyl sebacate, dibenzyl phthalate and the like. Othertypes of plasticizers, such as esters of inorganic acids, includingtricresyl phosphate, octyl diphenyl phosphate and the like, alkydderivatives of rosin, chlorinated paraffine, high molecular weighthydrocarbon condensates and the like can also be used. The plasticizeror blend of plasticizers is chosen to yield a composition of the desiredviscosity and/or foaming characteristics. In addition, the plasticizershould preferably have a low vapor pressure at the temperatures requiredto fuse the resin. A vapor pressure of 2 millimeters of mercury or lessat 400 F. has been found particularly satisfactory.

Minor amounts of stabilizers are usually incorporated in the coatingcompositions to reduce the effects of degradation by' light and heat.Suitable light stabilizers include phenylphthalate, phenyl benzoate,o-tolyl benzoate, o-nitrophenol, and organic phosphates and othercomplexes of such metals as barium, cadmium, calcium, zinc, strontium,lead, tin and the like. Suitable heat stabilizers include sulfides andsulfites of aluminum, silver, calcium, cadmium, magnesium, cerium,sodium, strontium, and the like, leucine, alanine, oand p-amino benzoicacid and weak acid radicals including ricinoleates and abietates, andthe like. Normally, the compositions contain about 0.5 to about 5 partsstabilizer per parts resin. The stabilizer in foamable compositions canexert influence on the decomposition of the blowing agent. Somestabilizers serve as catalyst causing the decomposition to take place ata lower temperature.

The coating compositions can contain pigments in accordance with theparticular color desired. Any of the organic and inorganic pigments wellknown in the art for plastic compositions can be used. Normally, fromabout 0.5 to about 5 parts pigments per 100 parts resin are used.

The foamable compositions contain, in addition, an effective amount ofblowing agent. The larger the amount of blowing agent within practicallimits used, the greater is the expansion of the foam. Foam densities offrom 12 to about 40 pounds per cubic foot can readily be obtained. Suchresults are attainable with from about l to about 20 parts blowing agentper 100 parts resin. About 2 to 10 parts blowing agent per 100 partsresin is particularly effective for the production of foams of a densitywhich are most desirable for use in producing floor coverings inaccordance with the invention.

Blowing agents are well known in the an and the particular blowing agentselected usually depends on such matters as cost, resin and densitydesired. While many compounds decompose by giving off a gas, only arelatively few are produced commercially in quantity. Complex organiccom pounds which, when heated, decompose to yield an inert gas and haveresidues which are compatible with the resin are preferred as blowingagents. Such materials have the property of decomposition over a narrowtemperature range which is particularly desirable to obtain a good foamstructure.

Typical types of blowing agent which can be mentioned includesubstituted nitroso compounds substituted hydrazides (RSO NHNHR),substituted azo compounds (RN=N-R), acid azides (RCON,,), guanylcompounds and the like wherein R and R are hydrogen or hydrocarbongroups usually containing from one to ten carbon atoms.

The blowing agents which have found the most widespread use are thosecompounds having the NN or N=N- linkages which decompose at elevatedtemperatures to yield an inert gas high in nitrogen. These compoundshave the general formula wherein a, b, c, and d are hydrocarbon groupspreferably containing up to ten carbon atoms, or hydrogen with at leastoneof the groups being a hydrocarbon group. Many of these hydrocarbongroups contain additional nitrogen groups such as hydrazide, amido,nitro, nitrile and the like. The presence of such groups is alsodesirable since they can readily react with the inhibitor to formderivatives having different decomposition temperatures. 7

'Typical blowing agents with their decomposition temperature ranges areshown in Table l:

Additional blowing agents which can be mentioned are N .N'dinitrosopentamethylenetetramine, aminoguanidine bicarbonate.p,p'-thiobis (benzene sulphonhydrazide) p.p'-diphenylmethanedisulphonohydrazide, benzene mdisulphonhydrazide, benzene sulphonhydrazide, terephthalazide, benzazide, p-tert.-butyl benzazide,phthalazide, isophthalazide, 1,3-diphenyltriazene,azohexahydrobenzonitrile. azo dicarboxylic acid diethyl ester,naphthalene-1,5- disulfonyl hydrazide and biuret.

Blowing agents for use in the invention must be decomposed an effectiveamount at a temperature below the decomposition temperature of the resinused. The preferred blowing agents are those that decompose above theelastomeric point of the resin composition since this enables at leastpartial gelling of the foamable coating so that a design can readily beprinted on its surface; Such blowing agent usually decomposes above 200F. As an illustration, with the preferred vinyl chloride polymers, ablowing agent decomposing between about 300 F. and about 450 F. can beused. The minimum initial decomposition temperature must be sufficientlyhigh to prevent premature gas evolution occurring during processing. Insome instances, a combination of blowing agents can be used toadvantage.

It iscommon practice to add accelerators or catalysts to thecompositions to accelerate the decomposition of the blowing agents,reduce the decomposition temperature and/or narrow the decompositiontemperature range. Common accelerators are various metal salts such asdibasic lead phosphite, dibasic lead stearate, dibasic lead phthalate,dibasic lead acetate, basic lead acetate, lead stearate, lead acetate,lead oxide, tribasic lead maleate, tetrabasic lead naphthenate, leadfumarate, lead 2-ethyl hexoate, and similar lead salts, zinc laurate,zinc oxide, zinc stearate, zinc carbonate, zinc 2-ethyl hexoate, zincdi-n-octoate, zinc naphthenate, and similar zinc salts, cadmium octoate,cadmium oxide, cadmium acetate, cadmium naphthenate, cadmium stearate,barium stearate, calcium stearate, nickel stearate, aluminum stearate,magnesium stearate, tin stearate, dibutyl tin maleate, and dibutyl tinoxide. These agents can also serve as stabilizersfor the composition. Inthe specification and claims the term blowing agent" is intended toinclude not only the blowing agent or chemical itself, but also thecombination of a blowing agent with an accelerator.

The foamable composition is formed into a film of the desired thicknessand then heated to gel the composition to give a good printing surfacefor the application of the inhibitor. In this specification and claims,the term gel" includes both the partial (at least the elastomeric point)and complete solvation of the resin or resins with the plasticizer(fused). The heating is limited as to the time and temperature toprevent the decomposition of the blowing agent in the composition. Whenusing the preferred polyvinyl chloride composition, the temperature ofthe composition is preferably raised to about 240 F. to about 275 F.Generally, the actual oven temperature would be a slightly highertemperature. If the foamable composition is to be formed into aself-supporting film, then the temperature would conventionally be highenough to fuse the composition.

The degree of foaming of a typical plastisol formulation using differentconcentrations of blowing agent is shown in the Table 2:

TABLE 2 Parts Azodicarbonamide Ratio of foam thickness per 100 partsresin to original thickness Density (lbs. per cu. ft.)

It has been found that density of from about 10 to 30 pounds percubicfoot produces the most useful products.

Table 3 gives the preferred temperature and time relationship using thepreferred polyvinyl chloride resin:

TABLE 3 Resin Oven Exposure Film condition 1 temperature temperaturetime (F.) (F.) circu- (seconds) lating air Elastomeric point... 240-300250-400 10-200 0.014 inch plastisol on 0.25 inch cellulosic felt baseimpregnated with 9 percent vinyl acetate and 30 petroleum hydrocarbon.The sample was supported on a wire screen in the oven.

The time required to reach the elastomeric point will depend in part onthe film thickness and particular base as shown in Table 4:

TABLE 4 Base Film thickness Time/temperature (inch) (seconds/ F.)

A 0.008 45/300 A 0.014 69/300 B 0.014 /300 l A cellulosic felt of 0.025inch thickness impregnated with 25 percent vinyl acetate homopolymer.

z A cellulosic felt of 0.043 inch thickness containing 5 percent of acured ureaformaldehyde resin and 25 percent of butadiene-acrylonitrilepolymer.

allows better control of the concentration of inhibitor applied. 1f theinhibitor is not soluble in the carrier, it can be dispersed with thecarrier in the conventional paint-making technique to produce a finedispersion. One of the easiest methods of applying theinhibitor-containing composition is by utilizing any of theconventional'printing techniques such as silk screen, offset or directrotogravure printing. As previously indicated, the inhibitor compositioncan be transparent orpigmented. It is conveniently formulated in themanner ofa printing ink. Such compositions usually contain a carrier forthe pigment, such as a vinyl resin, and, in some cases. a plasticizerfor the resin to give good adhesion to the printing surface. Theinhibitor for the blowing agent is an agent which alters thedecomposition temperature of the blowing agent in the area of thefoamable composition above or below where it is deposited. By varyingthe concentration of the inhibitor. the thickness of its application orits penetration (solubility or diffusibility) rate into the foamablecomposition, the degree of suppression or acceleration of thedecomposition of the blowing agent can be controlled to produce foamlayers of various heights or thicknesses. Unusual design effects can beobtained when'the foamable composition is printed with a multicoloreddesign wherein some of the ink compositions contain varying amounts ofinhibitor and others do not contain any inhibitor.

The choice of an inhibitor for the blowing agent will depend on a numberof factors. The most important are the particular blowing agent utilizedin the system, the stabilizer and plasticizer in the composition and thefusion and decomposition temperature of the resin. Since all of thesefactors play a part, it is important to determine the suitability of anyparticular system by a simple test. The foamable composition to betested is coated, or otherwise applied, on a base, heated to 1 gel orpartially harden the composition if this can be accomplished withoutdecomposing the blowing agent. Spaced parallel lines of the test inkcontaining the inhibitor are then applied on the surface of the gelledcoating in various concentrations, as for example, 5, 20 and 50 percentof the inhibitor. The sample is then carefully heated to fuse thecomposition and decompose the blowing agent in the areas desired. Theeffect of the particular inhibitor with the particular composition andconditions can readily be observed by viewing a cross-sectional cut ofthe sheet. As a general rule, it is desired to have at least 20 F.difference between the temperature at which the blowing agent willdecompose and that at which the inhibited blowing agent will decompose.If a blowing agent is utilized that decomposes below the gel temperatureof the composition, the inhibitor can be applied to the base and thenthe foamable composition applied over the inhibitor. Alternately, theinhibitor can be applied to the surface of the viscous foamable coatingprior to heating.

The chemical composition of blowing agents varies widely and, therefore,the type of compound utilized as an inhibitor will vary. As indicatedabove, a simple test can be carried out to determine the usefulness ofany particular compound. Compounds which have been found to be effectiveas inhibitors to alter the decomposition temperatures for blowing agentswhich contains the N=N- or NN linkages are the following groups:

(1) Organic acids, and particularly such as maleic,fumaric, adipic,malic, citric, salicylic, trimellitic, pyromellitic, malonic,1,2-phthalic, anthranilic, oxalic, formic, furoic, benzoic,2,6-dihydroxybenzoic, sorbic, levulinic, stearic, myristic, trimesic,oleic, octanoic, o-nitrobenzoic, isosebacic and glutaric,trans-l,2-diamino-cyc1ohexane tetraacetic acid monohydrate,4-methoxybenzoic, dihydroxytartaric, oaminobenzoic, m-aminobenzoic,p-aminobenzoic, lnaphthoic, terephthalic, dl-mandelic, azelaic,nitrilotriacetic, trichloroacetic, barbituric, Z-pyridinecarboxylic,2,3-pyridinedicarboxylic, ascorbic acid, and abietic acid. As a generalrule, the most useful acids are those having at least two carboxylgroups or those having at least one carboxyl group and one hydroxy groupand which contain from 2 to 12 carbon atoms.

(2) Organic acid halides preferably which contain from 2 to 20 carbonatoms and particularly the chlorides such as trimellitic anhydridemonoacic chloride, stearoyl chloride, phthaloyl chloride, benzoylchloride, ,palmitoyl chloride, cinnamoyl chloride, fumaryl chloride,l-naphthoyl chloride, terephthaloyl chloride, p-nitrobenzoyl chloride,4-methoxybenzoyl chloride, isophthaloyl chloride, terephthaloylchloride, trichloroacetyl chloride, bromoacetyl bromide, chloroacetylchloride, phenylacetyl chloride, acetyl bromide, n-butyoyl chloride,propionyl chloride, iso-valeryl chloride, n-valeryl chloride,Z-bromopropionyl bromide, dichlo'roacetyl chloride, oxalyl chloride,lattroyl chloride, myristol chloride, palmitoyl chloride, succinylchloride, hexanoyl chloride, hydrocinnamoyl chloride, adipyl chloride,isobutyryl chloride, 4-methyl-n-valeryl chloride, crotonylchloride,2-chloropropionyl chloride, Z-phenoxypropionyl chloride,phenoxyacetyl chloride, propionyl bromide, isobutyryl bromide, n-valerylbromide, 2-bromo-2methylpropionyl bromide, sebacyl chloride.cyclohexanecarbonyl chloride, ethyl oxalyl chloride, lO-undecenoylchloride, un-

chloride, 2,4-dichlorobenzoyl chloride, p-phenylazobenzoyl chloride, andl-intro-2-anthraquinonecarboxyl chloride.

(3) Organic acid anhydrides preferably those containing from 2 to 20carbon atoms such as maleic, phthalic, succinic, pyromelliticdianhydride, citraconic, pyrotartaric, dodecenyl succinic, trimellitic,tetrahydrophthalic, tetrachlorophthalic, hexahydrophthalic,endo-cis-bicyclo [2.2.1] hept-5-end-2,3-dicarboxylic anhydride,3,3,4,4-benzophenone tetracarboxyl dianhydride,1,2:3,4-cyclopentanetetracarbortylic acid dianhydride, chlorendicanhydride, dichloromaleic anhydride, acetic anhydride, benzoicanhydride, chloroacetic anhydride, propionic anhydride, n-butyricanhydride, iso-butyric anhydride, n-valeric anhydride, hexanoicanhydride, n-heptanoic anhydride, citraconic anhydride, bicyclo(2,2,1)S-heptene-2,3-dicarboxylic anhydride,cis-4-cyclohexene-l,2-dicarboxylic anhydride, 7-oxabicyclo (2,2,1)heptane-2,3-dicarboxylic anhydride, maleo-pimaric acid anhydride,trifluoroacetic anhydride, pyrotartaric anhydride, glutaric anhydride,dichloroacetic anhydride, itaconic anhydride, 4-methyl-2- cyclohexanel,Z-dicarboxylic anhydride, tetrabromophthalic anhydride3-nitrophthalicanhydride, tetraiodophthalic anhydride, naphthalic anhydride.5-norborene- 2,3-dicarboxylic anhydride, 3-chlorophthalic anhydride,4-chlorophthalic anhydride, 4-methylphthalic anhydride, pyromelliticdianhydride.

(4) Polyhydroxy alcohols. The polyhydroxyl aromatic compounds, whichform a useful sub-class of alcohols, preferably contain two functionalgroups, and from 2 to 20 carbon atoms. Representative compounds includep-aminophenol, catechol, resorcinol, hydroquinone, pyrogallol,phloroglucinol, 4-tert-butyl-pyrocatechol, 2,5-ditertiary-butylhydroquinone, p-benzoquinone, l,8-dihydroxyanthraquinone,2,3-naphthalenediol, 2,5-dichloro-3, fi-dihydroxy-p-benzoquinone,2,7-naphthalenediol, l,3- naphthalenediol, l,5-naphthalenediol,monotertiary-butyl hydroquinone, alizarin, purpurin, morin,o-hydroxybenzyl alcohol, a-nitroso-B-naphthol, andp-nitrobenzene-azo-anaphthol. Aliphatic alcohols which can be usedpreferably contain at least two hydroxy groups and include mannitol,sorbitol, glycerol, ethylene glycol and diethylene glycol.

(5) Carbohydrates, such as d-maltose, d-galactose, dglucose andfructose.

(6) Nitrogen containing compounds as amines, amides. oximes, and thelike, such as ethanolamine, cyclohexylamine, benzylamine, piperazine,p-nitroaniline, acetoacetamide,

anilide, N,N-disalicylidene-l,2-propane diamine, ethylenediamine,triethylenediamine, N,N-diethylaniline, a-benzoin oxime, dimethylglyoxime, a-fun'l dioxime, diphenyl carbazone, saliclaldoxime, guanidinecarbonate, triethylene tetramine, N-chlorosuccinimide, piperazine,3,3-iminobispropylamine, p-phenylene diamine, nicotine, quinine,quinidine, 8-hydroxyquinoline, piperazine, l,3-dichloro-5,5-dimethylhydr'antoin, imidazole, l,l-phenanthroline monohydrate,p-nitrobenzene-azo-a-naphthol, l-(Z-pyridylazo)-2-naphthol, phthalichydrazide, hydrazobenzene, p-toluene sulfonhydrazide and maleic acidhydrazide. Hexadecyltrimethyl ammonium stearate, 'hexadecylpyridiniumchloride, l-ethyl quinaldinium iodide. The amine is preferably a primaryor secondary aliphatic monoor polyamine. The aliphatic portion maycontain an aromatic or cyclic grouping and be saturated or unsaturated.Cyclic compounds can, for example, have a 6 to 10 member ring and canhave from 3 to 12 carbon atoms. Certain of the tertiary aliphatic aminesalso are useful amines.

(7) Sulphur containing compounds such as thiols or mercaptans, sulfides,sulfones, sulfoxides, sulfonic acids, sulfonyl chloride, sulfonamides,sulfimides and the like, as. for example: 2mercaptobenzothiazole,a,a-dimercapto-pxylene, mercaptosuccinic acid, l-dodecanethiol,methanethiol lead .salt, trimethylolpropane tris(3-mercaptopropionate),benzothiazyl disulfide, tetraethylthiuram disulfide, butadiene sulfone,glycol dimercaptoacetate, a-monothioglycerol, tetramethyl thiurammonosulfide, carboxy methylmercaptosuccinic acid, thiodiglycolic acid,tetramethyl thiuram disulfide, ethylene thiourea, thiourea,diphenylthiocarbazone, l-cysteine, o-benzoic sulfimide,sym-diphenyl-thiourea, a-naphthalene sulfonic acid,4,4-biphenyldisulfoni c acid, Z-naphthalenesuIfonic acid,l-butanesulfonic acid, m-benzenedifulfonic acid, thioacetamide,p-toluenesulfondichlorol-ethyl-2-phenyl-2-thiourea, l,3-diethyl-2-thiourea, l-phenyl-2thiourea, 1 ,1 ,3,3-tetramethyl-2-thiourea, 2 ,5-dihydrothiophene-1,1-dioxide,p-toluenesulfonyl chloride, 2- naphthalenesulfonyl chloride, glyoxalsodium bisulfide, sodium dithionite, benzenethiol, l-butanethiol,p-toluenethiol, Z-naphthalenethiol, ethanethiol, alpha-toluenethio](benzyl mercaptan), 3-methyll -butanethiol, 1 -propanethiol,methanethiol, 2-propanethiol, l-heptanethiol, Z-methylpropanethiol,mercapto-acetic acid (thioglycolic acid), l-pentanethiol, glutathione;o-toluenethiol, m-toluenethiol, 1,2- ehtanedithiol, o-mercaptobenzoicacid,,2-methyl-2-propanethiol, 2-mercapto 6-nitrobenzothiazole,6-amino-2-mercaptobenzothiazole, 2-mercaptoethanol, ethylmercaptoacetate, o-aminobenzenethiol, toluene-3,4-dithiol,l-hexanethiol, 5-amino-2-benzimidazolethiol, 2-benzoxazolethiol,3-mercaptopropionic acid, l-dodecanethiol, Z-mercapto-acetanilide,

2-ethyl-1-hexanethiol, p-chlorobenznethiol, methyl mercaptoacetate,2,3-quinoxalinedithio, Z-furanmethanethiol, 2-phenylethanethiol,p-tert-butyl-benzenethiol, l-octanethiol. Z-(phenylthio) quinoline,ethyl Z-mercaptoethyl carbonate, 4-mercaptobutyric acid,2,3-dimercaptopropanol, 2,3-dihydroxy-1-,4-dithiolbutane, isooctyl3-mercaptopropionate, isooctyl thioglycolate, l-thioglycerol, thiomalicacid, methoxymethyl thioglycolate, phenylmercaptoacetic acid. 2,)-para-menthanedithiol, B-mercaptoethyl-3-mercaptocyclohexane.B-mercaptoethyl-4-mercaptocyclohexane, 3-chloropropanethiol-l, pinanylmercaptan, dithiolterephthalic acid, lauryl thioglycolate, stearylthioglycolate, lauryl B-mercaptopropionate, stearyl,B-mercaptopropionate, hydroxyethyl thioglycolate, hydroxyethylB-mercaptopropionate, ethylene bis-mercaptoacetate, ethylenebis-B-mercaptopropionate, trimethylolethane. tri-mercaptoacetate,trimethylolpropane tris-mercaptoacetate. pentaerythritoltetrakis-mercaptoacelate. pentaerythritol.tetrakis-B-mercaptopropionate, 3l orgnnotin sulfur. dibutyl tinmercaptopropionate. dibutyl tin bis-(lamrylmercaptide). alkyl tinmercaptidc. and benzyl thiouronium chloride.

(8) lsocyanates such as 2,4-tolyenediisocyanate, p,p'- diphenylmethanediisocyanate, bitolyene diisocyanate, methylene bis(4-phenylisocyanate), dianisidine diisocyanate, phenyl isocyanate, l-naphthylisocyanate, p-tolyl isocyanate, p-nitrophenyl isocyanate, Z-naphthylisocyanate, m-tolyl isocyanate, o-tolyl isocyanate, p-ethoxyphenylisocyanate, p-bromophenyl isocyanate, o-chlorophenyl isocyanate,mchlorophenyl isocyanate, p-chlorophenyl isocyanate, 2,5-dichlorophenylisocyanate, o-ethoxyphenyl isocyanate, onitrophenyl isocyanate,Z-biphenylyl isocyanate, m-nitrophenyl-isocyanate, 4-biphenylylisocyanate, o-methoxyphenyl isocyanate, p-methoxyphenyl isocyanate,p-methoxyphenyl isocyanate, tolylene-Z,4-diisocyanate,m-xylylene'diisocyanate, pxylylene diisocyanate, methylenedi-p-phenyldiisocyanate and p-phenylazophenyl isocyanate.

(9) Ketones and aldehydes such as cyclohexanone. acetylacetone,l,3-diphenyl-l ,3-propanedione, l-phenyH, 3-butanedione, glyoxal,preferred compounds within this class will contain two functionalgroups, i.e., polyketones or polyaldehydes.

(10) Phosphate and phosphite compounds such as nbutyl acid phosphate,diamyl amylphosphonate. trilauryl trithiophosphite, and phenylneopentylphosphite.

(11) Other interestingcompounds which exert inhibiting qualities are6,6-dimethyl fulvene, hexachlorocyclopentadiene, 2,4-dinitrophenol,n-hexyl chloroformate, pnitrobenzyl chloroformate, dibutyl tin maleateand positive chlorine compounds such as dichloroisocyanuric acid,trichloroisocyanuric acid, potassium dichloroisocyanurate,N-chloro-p-benzoquinone imine, dichloroamine, and halane. Some of theselatter compounds are contained in the above groups.

When blowing agents are utilized having a reducible bond such as an azogroup, a reducing agent is a partricularly effective inhibitor. Typicalreducing agents are hydroquinone, polyhydroxyaromatic compounds,phenylenedia mines, hydrazobenzenes, alkali metal dithonite, mercaptanssuch as a,a-dimercapto-p-xylene and mercaptosuccinic acid, and thereducing sugars.

As indicated previously, some of the inhibitor causes the contactedareas to be raised above the remaining layer by lowering thedecomposition temperature of the blowing agent. In some instances, ifthe foam layer is heated to a higher temperature this increaseddecomposition can also cause the areas to collapse from being overblown.Such a collapsed product can have substantially the same appearance asif the decomposition of the blowing agent was prevented.

The inhibitors will not be useful for all types of blowing agents.Aminoguanidine bicarbonate is best inhibited with anhydrides such asmaleic and trimellitic; N,N-dimethyl- N,N'-dinitroso-terephthalamide isinhibited by similar anhydrides and chlorides such as terephthaloylchloride, p,p-oxybis (benzene sulfonyl hydrazide) is inhibitedparticularly effectively by trimellitic anhydride, terephthaloylchloride, fumaric acid and hydroquinone. Diazoaminobenzene is inhibitedby maleic and trimellitic anhydride and p,p'-oxybis (benzene sulfonylsemicarbazide) is inhibited with maleic and trimellitic anhydride,fumaric acid and terephthaloyl chloride. It is interesting to note thatinhibitors such as these catalyze the decomposition ofN,N'-dinitrosopentamethylene tetramine resulting in raised areas whenthese inhibitors are applied. Care must be exercised in selecting theinhibitor to produce the desired results.

The inhibitor produces a differential in the amount of expansion of thecontacted areas as compared to the other areas when the heating of thecomposition is controlled to to permit the differential expansion. Thisresults from a lowering or raising of the decomposition temperature ofthecontacted blowing agent. The protions of the resinous compositionlayer on which the inhibitor is applied will be not known, but it isbelieved the inhibitor reacts with the functional group or groups onthe'blowing agent to form a compound or complex having a decompositiontemperature different from the blowing agent itself. The acid and acidanhydride'are believed to function in this manner. In the use of areducing agent, the azo group is reduced with hydrogen or a hydrocarbonradical. The inhibitor could also be interfering with the action of theaccelerator. It is believed that the metal accelerator will cause thehydrolysis of the amide group in such blowing agent as azobisformamideto form the corresponding salt. The inhibitor may slow down or stop thishydrolysis. Alternately, the inhibitor can function as a catalyst oractivator in changing the decompsotion temperature of the blowing agent.Another method is to utilize as the blowing agent in the resinouscompsotion a mixture of a blowing agent and an inhibitor or the compoundformed by such a combination.

A second inhibitor which will react or interfere with the firstinhibitor is applied to the surface of such a composition to cause thefirst inhibitor to be unavailable to the blowing agent which will revertto its original decomposition temperature. A typical illustration ofsuch a combination would be the use of an acid as one inhibitor and abase as the other inhibitor. The inhibitor can also form a compound withthe accelerator utilized to prevent its availability to lower thedecomposition temperature of the blowing agent. As an illustration, whenusing lead as an accelerator, the addition of a chloride ion donorcauses the formation of a lead salt which prevents the lead from servingas an accelerator. It has been found that certain chelating agents willchelate metal accelerators and thereby remove them from the system.

It is essential to cause the composition in the areas of application ofinhibitor to have a decomposition temperature which is sufficientlydifierent from that of the remaining areas of the composition to allowdifferential expansion. The fusion temperature of the polymercomposition, therefore, fixes the temperature range in which it isnecessary to operate to obtain differential decomposition.

The ability of the inhibitor to prevent or accelerate the decompositionof the blowing agents when applied only to the surface of the foamablecomposifion is not understood. The solubility or diffusability of theinhibitor in the foamable composition at the decomposition temperatureis a definite factor in the process. When utilizing inhibitors which arereadily soluble, the amount of inhibitor and the percentageconcentration of inhibitor have a marked effect on the degree ofinhibition. The insoluble, or slightly soluble, inhibitors can be finelyground as in the nature of pigment which makes them either readilysoluble or diffusible at operating temperatures.

The amount of material utilized in the ink will determine in largemeasure the degree of foam inhibition. Particularly good results havebeen obtained with from to about 75 percent of the inhibitor. Theefficiency of the system can be improved by placing a barrier coat overthe inhibitor, such as an acrylic resin coating, to prevent migration ofthe inhibitor into the non-foamable wear layer. 4

The wear layer utilized in this invention is a preformed, selfsupportingsheet comprising a thermoplastic resinous material. The thermoplasticresinous binder can be made up solely of thermoplastic resinous materialbut it normally comprises a mixture of thermoplastic resin andplasticizer.

The resins which may be utilized in the wear layer composition areidentical to those previously described as applicable for use in thefoamable resinous composition. Polymers of vinyl chloride have beenfound particularly effective in the formulation of the wear layer.Furthermore, the heat and light stabilizers previously described arealso applicable for inclusion in the wear layer compositions.

The wear layer composition also contains fillers and pigments inaccordance with the particular background color desired in the finishedproduct. Inert fillers such as silica, both amorphous and crystalline,whiting, talc, clay, pumice, limestone and the like are suitable.Pigments are selected in accordance with the desired color. For example,where a white background is desired, titanium dioxide and zinc oxideeither alone or with extenders such as barium sulfate, magnesiumcarbonate, magnesium silicate and the like can be used. For coloredbackgrounds, any of the well-known organic or inorganic pigments can beused.

It has been found that the presence of filler is virtually essential tothe invention in order to prevent shrinkage and deformation of the wearlayer. The amount of filler required will vary with the type of fillerbut best results have been obtained when the filler is present in atleast 25 percent by weight of the composition and not over 60 percent ofthe composition. Inasmuch as in the preferred embodiment of theinvention, the inhibitor is applied to the surface of the foamablecomposition with a printed design and such printed design is visiblewhen viewed through the wear layer, it is essential for the filler to betransparent or translucent. Platy tale is a particularly good filler ofthis type.

The wear layer is produced by preparing granules, chips, flakes or thelike of resinous composition material containing the required filler,coating the flakes with a plastisol and then calendering the mixtureinto a sheet without fusing the plastisol. The chips of composition arepreferably multicolored. Multicolored chips of resinous composition canbe conveniently prepared by mixing separate batches of different coloredresinous compositions which are thereafter granulated and the granulesadmixed in the desired proportions to give the wanted color combination.The mixed granules are then sheeted by any suitable means, such as bypassage through calender rolls or extruding, and the sheets thusproduced converted into the desired geometric shapes. It is preferredthat the thickness of the chips, granules or the like be substantiallyuniform, and, therefore, cutting them from a sheet is highlyadvantageous. The thickness of the chips are preferably from aboutone-third to about seven-eighths of the thickness of the decorative wearsurface layer to be produced and a chip thickness in the range of aboutone-half to about three-fourths is particularly effective. The thicknessof the wear layer can vary but the minimum thickness is 0.014 inch. As ageneral rule, the maximum thickness for wear layer of generalutilization is 0.050 inch. In addition, the size of the pigmentedcomposition chips is of particular importance to obtain the desireddecorative effect. The preferred range in face area is from about 0.05inch in diameter to about 0.5 inch in diameter.

The chips are then coated with a liquid resinous composition.Particularly desirable results have been obtained with a blend whichcontains about 25 percent to about 50 percent liquid composition andabout 75 percent to about 50 percent chips by weight. A range of about30 percent to about 40 percent liquid composition and about 70 percentto about 60 percent chips has been found particularly effective.

In accordance with one embodiment of the invention, the initialpreparation of the foamable resinous composition may be accomplished byapplying a layer of a resinous polymer composition containing a blowingagent to a base, heating the coating to at least partially gel thecomposition without decomposing the blowing agent to yield a relativelysolid surface, and printing or otherwise applying on the surface of thegelled sheet a composition containing an inhibitor which will alter thedecomposition temperature of the blowing agent within the composition.

As an alternate method, the foam inhibiting agent can be printed orotherwise applied to a supporting base and then the foamable compositionapplied over the inhibiting agent. The

base in this instance can be, if desired, a transfer sheet and thedesign applied to form a decalcomania. Additionally, the foamablecomposition can be formed into a fused or partially fused sheet withoutdecomposing the blowing agent, such as by calendering, and then theinhibitor applied to either surface of the sheet. As another alternatemethod, a non-foaming solid resinous polymer composition can be appliedover the foamable composition and the inhibitor applied on the surfaceof the solid composition. During heating, the inhibitor willmigratethrough the composition which does not contain a blowing agent into thefoamable layer. As is apparent in such a system, the concentration ofapplied inhibitor would have to be greater than if applied directly tothe foamable composition to obtain the same degree of embossing.

With regard to the application of the wear layer, this second stage ofthe process of this invention may be accomplished in a variety of ways.Thus, the resinous composition sheet may be applied directly to theinhibitor-containing composition, with or without an adhesive layer.Alternately the printed foamable layer can be heated so that it isparticularly tacky and then the wear layer brought into contact with thelayer.

The preferred method, however,is by laminating the wear layer sheet tothe foamable resinous composition at the time of formation of the wearlayer. Thus, the viscous mass comprising the pigmented chips and theresinous composition is fed to a pair of calender rolls. The distancebetween the calender rolls is preferably adjusted so that it is greaterthan the thickness of of the chips. lnthis manner, the viscouscomposition can be formed into a sheet without substantially distortingthe size and shape of the chips. The calender rolls are so heated as tocause partial solvation of the resin thereby converting the liquid massinto a solid, self-supporting sheet containing the chips. The contacttime'of the composition with the heated calender rolls is of criticalimportance in that sufiicient heat has to be added to the composition tocause theconversion of the liquid to a gelled solid sheet. The heatedsheet is then laminated to the printed foamable layer.

The critical property of the resinous wear layer, for purposes of theinvention, is its fluidity or viscosity at the range of temperaturesutilized to decompose the blowing agent. This condition is obtained bycalendering or otherwise forming the composition into a sheet at atemperature below the fusion temperature of the composition. This can beaccomplished for example when utilizing the preformed polyvinyl chloridecomposition by passage through roll heated at approximately 225 F. to300 F.

The multi-layered assembly comprising the foamable resinous composition,the inhibitor and the translucent wear layer is then heated to atemperature sufficient to fuse both resinous compositions by completelysolvating the resin with plasticizer and to decompose the blowingsystem. The temperature of the entire mass of composition upon thebacking must attain the fusion temperature of the resin in order toobtain a product of maximum strength and stain resistance. Using thepreferred vinyl resin, fusion is attained at a temperature of about 325F. to about 375 F. In addition, the entire mass of foamable compositionmust be heated to a point where the blowing agent is decomposed. Whenthe preferred high temperature blowing agent is used, foaming does notoccur until the resinous composition hasbeen fused. The heating must becarried out, however, at a temperature which allows decomposition of theblowing agent only in the areas desired. The heating also enables the,wear layer to assume the desired fluidity so that it may conform to theembossings. developing on the surface of the resinous composition.

If volatile components are usedin the compositions, care must be takenthatthey are essentially completely removed from the film priortofusion. This can be accomplished by heating the composition at atemperature substantially below the fusion temperature and minimumdecomposition temperature of the blowing agent for sufficient time toremove the volatile material-For example, if a hydrocarbon solventfraction (boiling point up to 350 F.) is used, heating. at 200 F. 250 F.for 5 minutes will remove sufficient material so that fusion and blowingat 400 F. can be accomplished with good cell structure and freedom fromblisters. Heating in order to effect fusion and foaming can bebroughtabout in a forced hot air oven; however, other types of heating can beused. For example, the product can be passed beneath radiant heatingelements; alternately, dielectric heating can be used.

The foamed and fused product after leaving the heating oven is permittedto cool. Cooling is particularly important since anypremature handlingof the product immediately after foaming might cause partial collapseand distortion of the foam structure. Cooling can be brought" about bymere exposure of the product'to the atmosphere; thus, the speed ofmotion of the backing along the processing apparatus and the spacingbetween the fusion oven and the end of the apparatus can be adjusted sothat the product is given sufficient time to cool. Alternately, coolingcan be accelerated by blowing jets of cooled airupon the fused andfoamedcomposition or by 'means of fine sprays of water upon the fusedand foamed composition or by utilizing cooling rolls.

After being cooled, the product is withdrawn from the processingapparatus. It can be used in the form of a sheet as produced or-can becut into tiles or other appropriate shaped dependingon the particularuse to which the product is to be put. Products produced in accordancewith the invention have the characteristics of excellent resilience,depending in part on the thickness of the foam layer. They are alsocharacterized by having a marked three-dimensional textured appearancein perfect register with a printed design, if desired. Still further,the products of the invention have good heat insulating properties byvirtue of the layer of foamed composition and thus are warmer in winterthan conventional resinous surface coverings.

In addition, the products exhibit excellent wear resistance, chemicalresistance and stain resistance as a result of the presence of atranslucent, decorative wear layer over the entire surface thereof. Thewear layer is observed to have penetrated every crevice of the embossedpattern.

The following examples will furtherillustrate the embodiment of thisinvention. In these examples, all parts given are by weight unlessotherwise noted.

EXAMPLE I This example illustrates the preparation of a wear resistant,embossed, resinous composition typical of the products of thisinvention.

Preparation of Foamable Resinous Composition A 0.035 inch thick asbestossheet backing was coated, in a wet thickness of 0.015 inch, with the.following foamable plastisol:

Parts Polyvinyl chloride (low molecular weight) 50 Polyvinyl chloride(high molecular weight) 50 Dibasic lead phosphate 1.5 Azodicarbonamide2.5 Titanium dioxide 5 Butyl benzoyl phthalate 55 Dodecyl benzene l0Gelling of the foamable plastisol was accomplished by heating thecoating for a period of 2% minutes in a 400 F. oven.

Thereafter, the following embossing ink was applied to sections of thegelled plastisol by means of a rotogravure printing technique:

Parts Fumaric acid 10 Vinyl chloride-vinyl acetate copolymer 7.5 Methylethyl ketone 47.5 Titanium dioxide 14.0

PREPARATION OF WEAR LAYER The' following plastisol composition wasformulated by thoroughly mixing the ingredients listed hereinbelow:

Parts Dioctyl phthalate plasticizer) 99 Butyl benzoyl phthalate l6Stabilizer 19.2 Polyvinyl chloride and dioctyl phthalate plastisol 48Dispersion grade polyvinyl chloride 320 Stearic acid (lubricant) 1.3

The translucent flakes which were used in conjunction with the abovedescribed plastisol composition in the preparation of the wear layerwere prepared from the following formulation:

Parts Polyvinyl chloride 1 Platy talc (filler) 50 Dioctyl phthalate(plasticizer) 32.5 Butyl benzoyl phthalate 4.5 Stabilizer 7.5 U.V. lightabsorbent 0.4 Pigment 6.0

The flake stock was formed into a translucent, 0.015 inch thick sheetwhich was then comminuted into square flakes of approximately 0.125 inchin maximum dimension.

The resulting translucent flakes were uniformly blended in theproportion of 35 percent, by weight, of clear plastisol to 65 percent,by weight, of flakes. The blend while at a temperature of about 70 F.was fed to two chromeplated calender rolls. The top calender roll washeated to 290 F. and the bottom calender roll was heated to 270 F. Thecalender rolls were spaced apart .to produce a sheet of about 0.030 inchin thickness. The sheet was allowed to remain in contact with the bottomroll for almost a complete revolution and thereafter stripped from theroll. The rate of sheet production from the bottom roll was 19 feet perminute.

LAMlNATlON AND EMBOSSING PROCEDURES The 0.030 inch calendered wear layerwas then laminated to the foamable plastisol composition by passing bothsheets to a laminator at a speed of 30 feet per minute, such that theink printed surface of the foamable composition was in intimate,face-to-face contact with the wear layer. The two sheets were subjectedto a drum temperature of 340 F. and a roll pressure of 575 psig. duringthe lamination procedure. It was thus the combination of heat, pressureand the adhesive qualitiesof the vinyl embossing ink that enabled thetwo sheets to form a uniform, thoroughly adhered laminate.

The resulting laminate was then passed, at a speed of 30 feet perminute, into an oven having four zones each of 30 feet in length. Thezones were heated to 300 F., 300 F., 405 F., and 400 F., respectively.During the heating operation, the laminate became fused and the blowingagent decomposed to form elevated cellular sections of the surface ofthe product. The product had a textured surface with the ratio of foamthickness to original thickness being 3:1, the raised areas representingthose sections which were not printed with the inhibitor-containingembossing ink.

in addition, the wear layer had totally conformed to the embossings onthe surface of the product. It provided the product with excellentresistance to wear, staining and chemical attack. Furthermore, thesurface decoration of the product was particularly unique and attractivein view of the precise retention of the desired embossed design and thecombination of the wear layer and the pigmented flakes.

Additional wear resistant, multi-layered resinous assemblies exhibitingproperties which are comparable to those of the assembly preparedhereinabove, may be prepared by utilizing any of the foamable plastisolcompositions and inhibitor-containing printing composition disclosed inUS. Pat. No. 3,293,108 in conjunction with any of the wear layercomposi- Lil LII

tions disclosed in US. Pat. No. 3,194,859, and said disclosures are tobe deemed fully incorporated herein.

Summarizing, it is thus seen that this invention provides for thepreparation of novel wear resistant, embossed resinous compositions.Variations may be made in proportions, procedures and materials withoutdeparting from the scope of this invention which is defined by thefollowing claims:

We claim: 1. In the process for producing a wear resistant, mul-'tilayered resinous assembly on a base, the surface of said assemblyhaving areas of contrasting thicknesses, said process comprising thesteps of: l incorporating a blowing agent into a resinous material; (2)forming said resinous material into a layer; (3) applying to portions ofsaid layer an inhibitor for said blowing agent which is capable ofpenetrating into said resinous material and altering the decompositiontemperature of said blowing agent; (4) applying a wear layer thereto;and (5) heating the resulting assembly to the decomposition temperatureof said blowing agent;

the improvement which comprises applying as the upper surface of saidmulti-layered assembly a preformed, selfsupporting, non-fused,translucent wear layer having a thickness of from about 0.014 inch to0.050 inch and comprisinga blend of from about 25 to 50 percent, byweight, of a resinous composition with from about to 50 percent, byweight, of thermoplastic decorative chips encompassed therein, and

heating the resulting assembly to effect the inhibition reaction and,thereafter, to decompose the blowing agent and fuse the resinouscompositions so as to effect expansion at the sites of decomposition andthe formation of 'the contrasting thicknesses on the surface thereof,said wear layer exhibiting sufficient fluidity during said heating tostrictly conform to the resulting contrasting surface thicknesses.

2. The process of claim 1, wherein said resinous material is a polymerof vinyl chloride.

3. The process of claim 1, wherein said blowing agent is selected fromthe group consisting of substituted nitroso compounds, substitutedhydrazides, substituted azo compounds, acid azides and guanyl compounds.

4. The process of claim 3, wherein said blowing agent decomposes aboveabout 200 F.

5. The process of claim 4, wherein said blowing agent isazodicarbonamide.

6. The process of claim 3, wherein said blowing agent contains anaccelerator therefor.

7. The process of claim 1, wherein said inhibitor is selected from thegroup consisting of organic acids, organic acid anhydrides, organic acidhalides, polyhydroxy alcohols, amines, amides, oxines, mercaptans,sulfides, sulfones, sulfoxides, sulfonic acids, sulfonyl halides,sulfonamides, sulfimides and iso cyanates.

8. The process of claim 7, wherein said inhibitor is fumaric acid.

9. The process of claim 7, wherein said inhibitor is at least partiallysoluble in at least one component of said resinous material below thedecomposition temperature of said blowing agent.

10. The process of claim 1, wherein said resinous material is heated inorder to at least partially fuse the resinous material prior to theapplication of said inhibitor and the decomposition of said blowingagent.

11. The process of claim 9, wherein said inhibitor is applied toportions of a base and said resinous material containing said blowingagent is applied over said inhibitor and base prior to said blowingagent.

12. The process of 1, wherein said inhibitor is applied to said resinousmaterial in a printing composition.

13. The process of claim 12, wherein said inhibitor is applied to saidresinous material in the form of a design by a rotogravure printingprocess.

14. The process of claim 1, wherein the resinous composition in saidwear layer comprises a mixture of a thermoplastic resin and aplasticizer.

The process of claim 14, wherein said thermoplastic resin is a polymerof vinyl chloride.

16. The process of claim 1, wherein said wear layer contains an inertfiller in a concentration ranging from about 25 60 percent, by weight.

17. The process of claim 1, wherein said decorative chips comprisepigmented, plasticized vinyl chloride polymer compositions.

18. The process of claim 17, wherein said decorative chips have athickness of from about one-third to seven-eighths of the thickness ofsaid wear layer and a diameter of from about 0.05 to 0.50 inch.

19. The process of claim 1, wherein said base is asbestos sheeting.

20. In the process for producing a wear resistant, multilayered resinousassembly on a base, the surface of said assembly having areas ofcontrasting thicknesses, said process comprising the steps of: (l)incorporating azodicarbonamide into a plasticized vinyl chloride polymercomposition:,(2) forming the resulting polymer composition into a layer;(3) applying fumaric acid to portions of said layer, said fumaric acidbeing capable of penetrating into said polymer composition and alteringthe decomposition temperature of said azodicarbonamide; (4) applying awear layer thereto; and (5) heating the resulting assembly to thedecomposition temperature of said azodicarbonamide;

the improvement which comprises applying as the upper surface of saidmulti-layered assembly a preformed, selfsupporting, non-fused,translucent wear layer having a thickness of from about 0.014 inch to0.050 inch and comprising a gelled, vinyl chloride polymer plastisolcomposition containing plasticized vinyl chloride polymer decorativechips encompassed therein, said plastisol composition being present insaid wear layer in a concentration of from about 25 percent, by weight,and said decorative chips being present in a concentration of from about75 50 percent, by weight, said chips having a thickness of from aboutone-third to seven-eighths of the 1 thickness of the final wear layer;and,

heating the assembly to effect the azodicarbonamidefumar- -ic acidinhibition reaction and, thereafter, to decompose the azodicarbonamideand fuse the vinyl chloride polymer compositions so as to effectexpansion at the sites of decomposition and the formation of thecontrasting thicknesses on the surface thereof, said wear layerexhibiting sufficient fluidity during said heating to strictly conformto the resulting contrasting surface thickness.

2. The process of claim 1, wherein said resinous material is a polymerof vinyl chloride.
 3. The process of claim 1, wherein said blowing agentis selected from the group consisting of substituted nitroso compounds,substituted hydrazides, substituted azo compounds, acid azides andguanyl compounds.
 4. The process of claim 3, wherein said blowing agentdecomposes above about 200* F.
 5. The process of claim 4, wherein saidblowing agent is azodicarbonamide.
 6. The process of claim 3, whereinsaid blowing agent contains an accelerator therefor.
 7. The process ofclaim 1, wherein said inhibitor is selected from the group consisting oforganic acids, organic acid anhydrides, organic acid halides,polyhydroxy alcohols, amines, amides, oxines, mercaptans, sulfides,sulfones, sulfoxides, sulfonic acids, sulfonyl halides, sulfonamides,sulfimides and isocyanates.
 8. The process of claim 7, wherein saidinhibitor is fumaric acid.
 9. The process of claim 7, wherein saidinhibitor is at least partially soluble in at least one component ofsaid resinous material below the decomposition temperature of saidblowing agent.
 10. The process of claim 1, wherein said resinousmaterial is heated in order to at least partially fuse the resinousmaterial prior to the application of said inhibitor and thedecomposition of said blowing agent.
 11. The process of claim 9, whereinsaid inhibitor is applied to portions of a base and said resinousmaterial containing said blowing agent is applied over said inhibitorand base prior to said blowing agent.
 12. The process of 1, wherein saidinhibitor is applied to said resinous material in a printingcomposition.
 13. The process of claim 12, wherein said inhibitor isapplied to said resinous material in the form of a design by arotogravure printing process.
 14. The process of claim 1, wherein theresinous composition in said wear layer comprises a mixture of athermoplastic resin and a plasticizer.
 15. The process of claim 14,wherein said thermoplastic resin is a polymer of vinyl chloride.
 16. Theprocess of claim 1, wherein said wear layer contains an inert filler ina concentration ranging from about 25 - 60 percent, by weight.
 17. Theprocess of claim 1, wherein said decorative chips comprise pigmented,plasticized vinyl chloride polymer compositions.
 18. The process ofclaim 17, wherein said decorative chips have a thickness of from aboutone-third to seven-eighths of the thickness of said wear layer and adiameter of from about 0.05 to 0.50 inch.
 19. The process of claim 1,wherein said base is asbestos sheeting.
 20. In the process for producinga wear resistant, multilayered resinous assembly on a base, the surfaceof said assembly having areas of contrasting thicknesses, said processcomprising the steps of: (1) incorporating azodicarbonamide into aplasticized vinyl chloride polymer composition: (2) forming theresulting polymer composition into a layer; (3) applying fumaric acid toportions of said layer, said fumaric acid being capable of penetratinginto said polymer composition and altering the decomposition temperatureof said azodicarbonamide; (4) applying a wear layer thereto; and (5)heating the resulting assembly to the decomposition temperature of saidazodicarbonamide; the improvement which comprises applying as the uppersurface of said multi-layered assembly a preformed, self-supporting,non-fused, translucent wear layer having a thickness of from about 0.014inch to 0.050 inch and comprising a gelled, vinyl chloride polymerplastisol composition containing plasticized vinyl chloride polymerdecorative chips encompassed therein, said plastisol composition beingpresent in said wear layer in a concentration of from about 25 - 50percent, by weight, and said decorative chips being present in aconcentration of from about 75 - 50 percent, by weight, said chipshaving a thickness of from about one-third to seven-eighths of thethickness of the final wear layer; and, heating the assembly to effectthe azodicarbonamidefumaric acid inhibition reaction and, thereafter, todecompose the azodicarbonamide and fuse the vinyl chloride polymercompositions so as to effect expansion at the sites of decomposition andthe formation of the contrasting thicknesses on the surface thereof,said wear layer exhibiting sufficient fluidity during said heating tostrictly conform to the resulting contrasting surface thickness.